DE2529509A1 - VALVE SEAL - Google Patents

Description

Dr.-lng. E. BERKENFELD · Dipl.-Ing. H. BERKENi-ELD, patent attorneys, Cologne Attachment file number

to enter 30 ^ J _uni ^ 75 _{my #} Name d. Ann ,. pQS I - SEAL INTERN AT I ON AL, INC

P 81/1 valve seal

The present invention relates to a sealing mechanism and, more particularly, to a valve sealing mechanism having a metal contact on metal to ensure a positive seal even under high temperature conditions or fire risk.

In U.S. Patent 3,642,248, a valve sealing mechanism is in the form of a wear ring having a shoulder and arranged in an undercut circumferential groove is described. This one points a continuous central rib which extends radially through the opening in the groove beyond the shoulder-shaped section. The circumferential surface of the rib then serves as a seat for and is in contact with a complementary sealing surface of a valve member.

This known wear ring is preferably combined with a 0-shaped support ring made of elastomeric material, which is between the The bottom of the groove and the shoulder-shaped section of the wear ring is seated. The support ring fulfills a double function. He pushes the wear ring out of the groove into firm contact with the sealing surface and further prevents leakage pressurized equipment behind the wear ring.

An important application of those described in this US Pat. No. 3,642,248 Throttle valves are used in systems for handling equipment at high pressure and high temperatures or in the case of flammable equipment that has a high risk of fire and can lead to high temperatures as a result. For these applications, it is proposed that the wear ring be made of fully hardened stainless steel and give it two to the outside to give widening side flanges, each from each side of the shoulder-shaped section radially opposite to the central rib extend (column 10, line 30 to column 11,

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Line 32).

With the expansion of the side flanges, a sealing force acting against the side walls of the groove is intended to be brought about. The inner circumference of the seat of the wear ring is designed so that between this seat surface of the wear ring and the sealing surface of the valve member, a radially acting sealing force acts comes. In this way, this wear ring made of stainless steel is placed laterally and radially under a form pressure. So that will at the interface between the seat surface and the sealing surface as well as on the contact line between the side flanges and the Walls of the groove achieve a positive seal even if exceptional temperatures damage or destroy the support ring made of the elastomeric material.

This stainless steel wear ring represents a effective "fireproof" seal. Metal-to-metal contact, however, results in more leakage than others Wear rings made from various plastics. It should be added that the production of metallic wear rings within the dimensional tolerances necessary for a correct preload is difficult and expensive.

One object of the present invention is to create an effective sealing mechanism for a "refractory" and other high temperature applications.

The invention further relates to a form under pressure Metal-to-metal sealing arrangement in combination with an elastic, non-metallic sealing ring to achieve a maximum sealing effect under normal conditions and with permanent sealing effect in the event of damage or destruction of the non-metallic sealing ring.

The invention further relates to a metallic valve seat arrangement for a metal-to-metal sealing contact working with a pre-pressure with a sealing surface of a valve member, whereby the sealing

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arrangement should be both simple and inexpensive to manufacture.

The invention further relates to a metallic valve seat arrangement in / form of an annular, thin-walled insert-like lip with an inner flange which is connected to a sealing surface of a valve member in Tight contact is.

The invention further relates to a metallic insert for a valve seat with an inner thin-walled insert-like lip for producing a sealing contact with a valve disc, the ring simultaneously representing a retaining ring for a conventional, elastic, non-metallic sealing ring,

The invention further relates to a metallic insert ring for a valve seat of the type described with such coefficients of thermal expansion of the valve disk and valve seat that the sealing effect increases with increasing temperature.

These and other goals are achieved with the inventive sealing «Mechanism achieved. It includes a structure such as a valve body with a channel with an inlet and an outlet for the operating medium flow, in the flow channel at one point An annular seat area enclosing the inlet and outlet, and a closure member, such as a valve disc with a sealing surface extending in the circumferential direction, the shape of which is matched to the sealing area.

The improved sealing mechanism of the invention further comprises a ring-shaped, undercut, insert-like lip, which in the Hand of the seat area is formed and has a free edge which points in the direction of the inlet of the flow channel. The inner catch of the free edge of the lip lies with the sealing surface of the Closing member in a predetermined fit in engagement Daeit a radial sealing force under a preload arises between the edge of the lip and the sealing surface of the closure member. The sealing surface of the sealing member is generally an in approximately spherical section. This facilitates the rotatable Sff-

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tion of the sealing member. The linear contact is preferably carried out in a plane at a distance downstream from the plane of the maximum disk diameter. Through an arrangement of the If the lip is designed so that its free edge points upstream, the sealing force, which is under a preload, is generated by the operating medium pressure increased, which acts from the inlet side of the channel against the undercut side of the lip. In this way If the operating fluid pressure rises, the radial pressure also increases Sealing pressure between the lip and the sealing surface of the valve member. In addition, when the operating pressure rises, the valve disc is moved downstream into the journal bearings. With that she will more firmly pressed into sealing engagement with the annular lip.

In the arrangement described above, the annular lip of the improved sealing mechanism forms an outer seating surface for engagement with a complementary sealing surface of a closure member for the flow channel. The arrangement can also be reversed. Then the annular lip forms an inner seating surface on the closure member for engagement with an outer sealing surface formed in the wall of the flow channel. the However, the first arrangement is preferred because it is metal under tensile stress shows better properties when compared to metal when subjected to compression.

A preferred embodiment of the present invention, which is particularly suitable for flow systems in which normal operating temperatures permit the use of resilient non-metallic seals, the annular lip-like seal metal on metal of the present invention comprises as the downstream mouth of an undercut groove for holding a conventional resilient Sealing ring, for example a wear ring with or without a support ring, as described in US Pat. No. 3,642,248. The elastic sealing ring forms the main seal and ensures minimal leakage under normal operating conditions. The metallic lip acts as an auxiliary seal and ensures a permanent seal should the elastic sealing ring be damaged or destroyed.

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In a particularly preferred embodiment, it is annular Lip formed in a special valve seat insert ring. This can also serve as a retaining ring for a conventional elastic sealing ring or wear ring. The annular lip can be work into the insert ring easily and inexpensively. It can then be attached to the seat area with machine screws or other conventional fasteners. The use of a separate Insert ring for the improved sealing mechanism of the present invention enables this sealing structure to be used when required can also optionally be installed in conventional valve bodies. Separate insert rings can also be made from metals and Subject to processes particularly suitable for metal-to-metal preloaded sealing functions. This may lead to properties that are beneficial to the material of the valve body or a other construction in which the sealing mechanism is to be installed is not suitable. In particular, the coefficient of thermal expansion of the material of the insert ring can be smaller than the thermal one Select the expansion coefficient of the disc. In this way, greater pressure forces and an improved sealing effect can be achieved with increasing temperatures.

Using the example of the embodiments shown in the drawing the invention will now be further described. In the drawing is:

Figure 1: an exploded perspective view

of a conventional pin valve, in which the preferred embodiment of the improved according to the invention Can be installed sealing mechanism,

Figure 2: a partial section through the preferred embodiment

the sealing mechanism in combination with a conventional one Wear ring and support ring in the valve shown in Figure 1 with the valve disc open,

Figure 3: a partial section similar to Figure 2, but with the valve disc closed,

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FIG. 4: a partial section similar to FIG. 3, but with operating medium introduced under pressure on the inlet side of the valve,

FIG. 5: a partial section similar to FIG. 4 with the representation of FIG by itself becoming effective sealing function of the invention according to the mechanism in case of disintegration or a loss of the wear ring, and

FIG. 6: a partial section through an embodiment similar to FIG

according to FIG. 5 but without the replacement ring provided for the wear ring.

To better understand the construction and operation of the improved sealing mechanism of the present invention, this will now be described using an embodiment which is built into an otherwise conventional flap or spigot valve. Figure 1 shows a such a valve in an exploded perspective view.

The valve shown in Figure 1 contains a valve body 1 in the form a flat annular disc with an inner channel 2 with an inlet 3 and an outlet 4. The downstream or The outlet side 5 of the valve body has an annular constriction 6 for receiving a rick holder ring 7 flush. This one will screwed on with flat head screws 8. The retaining ring 7 is used for fastening a sealing or wear ring 9 and a support ring 10 in one in the downstream edge of the channel 2 incorporated circumferential groove 11. In the following it will be explained that this retaining ring 7 also represents the seat arrangement of the improved sealing mechanism according to the invention.

A valve disk 12 with a sealing surface 13 provided on its circumference is inserted into the channel 2 and is there between a opening position in which it is essentially parallel to the axis of the Channel 2 runs, and a closed position in which it runs substantially perpendicular to the channel, rotatable. In its closed position, its sealing surface 13 rests against the valve seat structure.

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This includes the wear ring 9 and the retaining ring 7.

The devices for the pivotable fastening of the valve disc in the channel for the purpose of rotation between the opening and the closed position contain a valve pin 14. The valve pin 14 further passes through a bore 18 which is drilled through by a diametrical projection 19 on the upstream side of the valve disc. The valve disc is connected to the pin by means of the studs 20.

Leak through along the top of the valve pin 14 is prevented with a normal pack. This pack contains a spacer 21 and elastic stopper rings 22, These are in the Blind hole 17 is pressed against the top of the sleeve 15. For this purpose, the sealing ring 23 and the plate 24 are also placed on threaded bolts 26 screwed nuts 25 printed down. In its sockets is the valve pin 14 by hand or a motor, not shown in detail and flanged to the upper square end 27 turned.

The construction and operation of the improved inventive Sealing is now shown in detail in FIGS.

Figure 2 shows a portion of the assembled sealing arrangement of the valve according to Figure 1. The shape of the one shoulder Sealing ring 9 and the support ring 10 and their arrangement in the groove 11 are essentially as in the already mentioned U.S. Patent 3,642,248.

The improvement according to the invention is characterized by a annular undercut, skirt-like lip 28, which is incorporated into the retaining ring 7, and the opening on the downstream side the groove 11 represents. The lip 28 extends generally upstream and it has a free edge 29, the flow

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runs upwards towards the inlet of the channel 2. the The inner surface 30 of the lip 28 has a diameter at its free edge which is smaller than that of the channel 2. The diameter of the Inner surface 30 is roughly the same as the diameter of the seat surface 31 of the sealing ring 9.

The diameters of both the inner surface 30 of the lip 28 and the Seat surface 31 of the sealing ring 9 are also smaller than the diameter of the sealing surface 13 of the valve disc 12. If this is located in In their closed position shown in FIG. 2, the seat surfaces 30 and 31 of the lip 28 or of the sealing ring 9 lie on the sealing surface 13 of the valve disc 12. This takes place in the Feststiz and a radial The sealing force acts between the seat surfaces and the sealing surface of the valve disc.

For the purpose of maximum sealing effect and minimum torque when adjusting, the sealing ring 9 is preferably made of an elastic one Plastic material such as tetrafluoroethylene. Such a material has a relatively low modulus of elasticity. The sealing force that can be achieved from the fastening between the ring and the disk is also relatively small. Using a elastomer support ring 10 of suitable size are thus by squeezing this ring together generates additional sealing forces. Figure 2 shows this picture. The result of a given The radial sealing pressure resulting from the sealing force acting on the sealing ring can also be increased by cutting an annular section 32 out of the sealing ring 9 to reduce the contact surface between the ring and the valve disk.

Figures 4 and 5 show the effect of inserting below Pressurized operating medium on the inlet side of the valve. In FIG. 4, the pressurized operating medium indicated by the arrow tends to push the upstream end of the sealing ring 9 away from the upstream side wall 33 of the groove. The operating fluid then runs into the area between the sealing ring and the bottom 34 of the groove, from where it presses the elastomeric support ring into the downstream corner of the groove. As a consequence of this-

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from increases the sealing effectiveness of the known combination from sealing and support ring, as described in the already mentioned US Pat. No. 3,642,248. As long as the sealing ring and the support ring are completely and fully operational, the pre-pressurized metal lip 28 of the present invention carries little or nothing nothing to seal.

However, if the sealing ring 9 and the support ring 10 are for example Damaged or destroyed by fire, the situation shown in FIG. 5 results. In this case, the pressurized fills Operating means the groove 11 out there and the only contact between the valve seat and the disc is between the inner surface of the free edge of the lip 28 and the sealing surface 13 of the valve disc.

The reason for undercutting the lip to form a thin-walled apron-like ring results when looking at Figure 5. The lip 28 acts like a spring member that with the valve disc in a fit with considerable radial Can bring excess without affecting the serviceability of the valve is excessively impaired. A nominal radial A fit of at least 0.125 mm is necessary even for the smallest valve sizes in order to ensure a sealing seat for all valve and seat combinations under normal manufacturing tolerances obtain. The outer surface 35 of the lip 28 also forms a surface on which the pressure of the indicated by the arrows System can build and thus creates additional sealing forces. The shape of the lip therefore leads to a self effective sealing, which increases the sealing effect with increasing system pressure.

The sealing effectiveness of the lip can also increase with increasing temperature, if the coefficient of thermal expansion of the Lip-forming material is smaller than the coefficient of thermal expansion of the valve disc. For example, if this consists of stainless steel and if the ring is made of carbon steel, the disc circumference will increase more rapidly as the temperature rises the circumference of the lip and the disk thus more firmly on the lip

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press the ring. Depending on the operating conditions of the valve It is also possible to choose materials with different thermal expansion coefficients.

The combination of a well-known sealing ring and support ring with The metal-to-metal sealing according to the invention as shown in FIGS. 2-4 is in most cases the preferred embodiment for achieving maximum sealing. Figure 6 shows an alternative embodiment. Here the seal according to the invention is used in combination with a single sealing ring. These Embodiment is indicated when the operating conditions are detrimental to the elastomeric material of the support ring, generally natural rubber or synthetic rubber. As before can the sealing ring can be made of an elastic material such as TFE. In extreme cases it could also be made of metal, if a double metal seal is on Metal is necessary.

As shown in Figure 6, the sealing ring is under normal Conditions alone effective and seals both at the interface between the seat surface 31 and the sealing surface 13 as well as behind the sealing ring at the interface between the downstream side wall 36 of the groove and the flange of the sealing ring 9. This happens as a result of the pressure building up behind the sealing ring, which acts radially inwards and laterally outwards against the rear sides of the seat sections and side flanges of the ring.

Although the preferred embodiment of the undercut, annular, apron-like sealing mechanism of the present invention is in combination with the construction of the sealing and support ring according to US Pat. No. 3,642,248, the sealing mechanism can also be combined with other conventional elastic sealing members if necessary or use alone with yourself. In constructions where the undercut apron-like seal is used alone is to be, the upstream groove does not need to be formed for an elastic sealing ring. With standard valves however, for example with the groove arrangement inclined in FIG.

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results depending on the intended operation for the valve conditions a wide variety of sealing combinations.

The preferred embodiment for the sealing mechanism of the present invention is also available as part of a restraint or Insert ring has been shown. The undercut apron-like lip of the invention can be worked directly into the wall of the flow channel of a valve body. However, a separate insert ring has several advantages. Some of these benefits, like the ease of processing and the use of materials particularly suitable for a valve seat have already been described above.

The shape of the retaining ring of the embodiment shown also allows easy insertion of the sealing ring and / or the support ring and further leads to a certain degree of self-centering. This will cause a certain mis-centering of the Valve disc lifted in the valve body. This self-centering results from closing the valve disc before tightening the fastening screws of the retaining ring. The play in the screw holes allows some movement of the ring too its adaptation to the valve disc. The screws are then tightened.

It was previously stated that the undercut, apron-like lip acts like a spring member. When constructing a For a specific application it is therefore important to ensure that the yield point of the metal is not exceeded will. For a given valve size, the equation for determining the maximum permissible radial oversize can be derived from Easily derive the basic equation for elastic materials and the geometric shape of the annular lip.

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where / \ r is the maximum permissible radial oversize in inches,

S is the maximum allowable tensile stress in the lip in pounds per square inch,

E is the Young's modulus for the material forming the lip in pounds per square inch and

d is the average diameter of the lip in inches.

It has been determined experimentally that a radial oversize of about 0.005 "to about 0.010" for valve sizes in the range of 1.5 to 36 inches in diameter will give satisfactory results. at For sizes above 36 inches, it is expected that the radial oversize should be increased from about 0.008 inches to about 0.015 inches. These numbers are intended as an example and not limiting to be seen. They relate to those dimensions that are obtained after grinding in the valve disc and the seat after several opening and closing processes can be measured. Even with ground fitting surfaces, it was found that the measured Inner diameter of the undercut lip during the first ten Valve duty cycle increased 0.015 "to greater than 0.020". A predetermined pre-load could thus be lost, if this initial wear and tear is not taken into account.

In addition to limiting the radial excess, so that it remains within the elastic limit of the material forming the sealing lip, it is also important that the cross-sectional area of the Lip (width times thickness) to limit in order to keep the tensile stress prevailing in the lip below a value that is based on refers to the maximum torque required for the valve. This relationship between the tensile strength and the operating torque leaves determine oneself experimentally. The corresponding cross-sectional area A is given by the equation:

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F. d
^{A =} 2E.

where F is the maximum permissible tensile force in pounds,

d is the average diameter of the lip in inches,

E is Young's modulus in pounds per square inch and / \ r is the radial oversize in inches.

In order to explain to those skilled in the art how the present invention can be applied to a range of valve sizes, in the following table representative dimensions of the lip for three Valve sizes given. All dimensions are to be understood in inches;

Valve size, lip width, lip thickness

6 0.135 0.020

10 0.140 0.025

20 0.180 0.025

In each of the above examples, the width of the undercut lip i is between at least five times and less than ten times its thickness. Although the operating range of the seal according to the invention is not limited to values between these ratios, they represent preferred practical limits. With a ratio of width to thickness of about 5, the torque is slightly higher than desired and the area exposed to the system pressure is too small. to achieve noticeable self-actuation. At a ratio of more than about 10, the lip can be difficult and the process without exceeding '· ^"1 of the elastic limit of the material achievable maximum preload falls within the optimum values.

The preferred embodiment of the improved sealing mechanism

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the present invention has thus been illustrated and described. However, it will be understood by those skilled in the art that the invention is not necessarily limited to the embodiments described is and that those skilled in the art can also determine further arrangements and configurations that are within the scope of the inventive Teaching of the above disclosure.

The preferred embodiment has been explained, for example, with the annular lip undercut here, which with the Circumferential sealing surface forms an outer seat member on a valve disc. The positions of the sealing surface and the annular lip can be exchanged, however, so that the lip of the valve disc or a similar closing element for the internal flow channel is carried, and the sealing surface forms the valve seat.

In such an arrangement, the annular lip would be pre-pressurized. Since the tensile strength of metal is now essential is better than the compressive strength, that arrangement is preferred in which the metal pipe surrounds the sealing surface. Other Materials that can be used for the lip and that have superior compressive strengths, such as possibly ceramics, could be useful for the other embodiment are better suited.

PATENT CLAIMS

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Claims (13)

Dr.-lng. E. BERKENFELD · Dipl.-I |> g. H, BiRKENFELD, patent attorneys, Cologne June 30, 1975 my. ZH'w POSI-SEAL INTERNATIONAL ₁ INC. PATENT CLAIMS Γΐ .J valve seal for a valve with a valve body with an inlet opening, with an outlet opening and an inlet and outlet / connecting flow channel, with a first annular surface which is formed in the wall of the flow channel at a point i between inlet and outlet, a valve disc having a second annular surface formed on its circumference, one of these two surfaces forming a seating area and the other surface forming a sealing surface, and means for pivotably supporting the valve disc in the channel for rotating the second annular surface into and out of engagement with the first Ring surface, characterized in that a valve seat insert ring is attached in the seat area, the insert ring has a thin-walled apron-like lip, the edge of the lip points upstream in the direction of the inlet of the channel and is in engagement with the sealing surface in a predetermined fit to form a radial sealing force between the Edge of the lip and the sealing surface when the second annular surface is rotated into engagement with the first annular surface, a groove is formed in the seating area upstream of the insert ring and the edge of the lip of the insert ring is formed as the downstream mouth of this groove, and a resilient sealing ring lies in the groove and protrudes with a seat on its periphery through the mouth of the groove for sealing engagement with the sealing surface, provided that the valve disc is rotated so that the second annular surface is in engagement with the first annular surface. 2. Valve seal according to claim 1, characterized in that the material forming the valve disk has a coefficient of thermal expansion which is at least equal to the coefficient of thermal expansion of the insert ring. 3. Valve seal according to claim 1, characterized in that it has a flow channel in a valve body between an inlet and an outlet, in the channel between inlet and outlet 509884/0437 Outlet a valve seat is formed, a valve member with a is provided on its circumference sealing surface and this is rotatably mounted in the channel for rotation in a Closing or opening position on the valve seat, thereby characterized in that a circumferential groove is formed in the wall of the flow channel at the point of the valve seat, which Grooves an upstream sidewall pointing toward the inlet of the flow channel and one toward the Having the downstream side wall pointing outlet of the channel, an elastic sealing ring is arranged in the groove and with an inner seat arranged on its circumference protrudes through the mouth of the groove for sealing engagement with the Sealing surface of the valve member for forming a primary seal with this valve member, and on the downstream side wall of the mouth of the groove an undercut apron-like Lip is formed extending from the downstream side wall toward the upstream side wall, and the inner periphery of the edge of the lip with the sealing surface of the valve member in a predetermined snug fit in engagement with to form this a secondary seal, so that this secondary seal prevents a passage of fluid between the inlet and the outlet of the channel in the event of damage or destruction of the elastic sealing ring. 4. Valve seal according to claim 3, characterized in that the elastic sealing ring consists of a non-metallic material. 5. Valve seal according to claim 3, characterized in that the elastic sealing ring consists of a plastic. 6. Valve seal according to claim 3, characterized in that the material forming the disc has a coefficient of thermal expansion which is at least equal to the coefficient of thermal expansion of the insert ring. 7. Valve seal according to claims 1-6, characterized in that 509884/0437 that in the wall of the flow channel in the seat area an annular undercut apron-like lip is formed, the lip has a free edge which is upstream in the direction the inner circumference of the free edge of the lip with the sealing surface of the closure member points to the inlet of the flow channel engages in a plane which is displaced downstream relative to the plane of the maximum circumference of the closure member and the engagement takes place in a predetermined tight fit, so that between the edge of the lip and the sealing surface of the closure member a radially acting sealing force arises, so that there is a prevailing between the inlet and the outlet of the flow channel positive pressure differences act on the undercut side of the lip and the radial sealing force w between them Increase the edge and the sealing surface of the closure member, and the closure member with this increase in the pressure difference in tighter Pressing tight engagement with the free edge of the lip. 8. Valve seal according to claim 7, characterized in that the undercut lip is rectangular in cross section and the width of the lip is much greater than its thickness. 9. Valve seal according to claim 7, characterized in that the width of the undercut lip is at least five times their strength lies. 10. Valve seal according to claim 7, characterized in that the width of the undercut lip is between about five and ten times its thickness. 11. Valve seal according to claim 7, characterized in that the radial oversize between the edge of the lip and the sealing surface of the closure member is at least about 0.125 mm. 12. Valve seal according to claim 7, characterized in that the radial oversize between the edge of the lip and the sealing surface of the closure member is between about 0.125 mm and 0.375 mm. 509884/0437 13. Valve seal according to claim 7, characterized in that a circumferential groove is formed in the flow channel upstream of the skirt-like lip and the edge of this lip the downstream opening of the groove forms, and an elastic sealing ring is located in the groove and with one located on its circumference Seat protrudes through the mouth of the groove for sealing engagement with the sealing surface of the closure member, when its sealing surface is in contact with the free edge of the lip. 509884/0437 Blank